Powder Weight

[StarMetal]

I have a question. Say you buy a new can of powder and you work up a load and measure out your charge. If you've had the powder a long time after that you know that the moisture content changes, especially with pouring it out of the can into your powder measuring device and then back again if you didn't use it all in the measure and finished reloading. So after a long period time we are told to reweigh the charge. Okay, we know the moisture content changed and that means the powder is slightly lighter. But lets say you don't reweigh it and use the same setting (take note for that particular lot of powder, not a different lot) is there going to be a big difference in it's burning rate? If so, how much? Unsafe? I'd like to know and if any of you have wondered this also.

Joe

[BCB]

Not trying to change the subject, but I start each reloading session by weighing a thrown charge of the previous power I was using. Example: I was recently reloading 28 grains of WC-844 one evening. I was throwing the charges and weighing every 7th one. They were right on the clam shell. The next morning I started reloading the same 28 grain load and the thrower was dropping them .3 grain less. So, I got out my exact weights for checking the accuracy of scales, and sure enough the scale was set at 28 grains. The powder was just being thrown light. Don’t know why. This happens more often than most people are aware. I reset my thrower every time I reload, even if it is an old time favorite and the charge of powder never changes—at least on paper…BCB

[Buckshot]

............I don't know how I figure in with the rest of the guys as to their habits, but this is what I do. First I have only one measure with any meaningfull repeatability that I could reset, and that's due to it's markings, a Lee (I hesitate to use their 'Perfect' descriptor) measure.

I always use the balance beam to weigh charges while setting the measure. After that I throw the charges. After doing ten I'll toss one back on the scale pan. I think that you're getting at a charge increase due to a moisture loss, ie more power getting dropped due to less moisture?

I don't know if this is really a big problem overall. I've done load confirmations one week later that have been 25 fps higher or lower in velocity then the previous test and I think this is more having to do with condition change between the days then anything else. Heck, I've shot stuff in the morning upon arrival at the range and then shot the same loads again later in the day that were 50 fps faster (WC852 Slow comes to mind) because it was 20* warmer.

Long gone are the days when I thought I needed the very last available FPS I could squeeze out of a cartridge, and I think up in this region is where any moisture loss would cause problems. In all actuallity I doubt that there is any perceptable loss in moisture in the way we treat our powders in a day to day scenario. In some places of high humidity, you might be getting MORE moisture vs less. I don't think that smokless powder is that suceptable to giving up or gloming onto moisture in normal reloading routines. At least as compared to black powder anyway.

...............Buckshot

[StarMetal]

To throw a fly in the ointment, most shotshell loaders have a fixed bushing to throw powder charges. Some presses have adjustable ones.

I'm not going to lie, if I have my Belding & Mull metering tube to throw say 4.0 grs of WW 231, as it is currently set now, I don't re-weigh and reset it...as long as my powder is from the same can and lot. I see no sense in it. Nobody, absolutely nobody goes in my reloading shop. So nothing is going to get changed. Yes, I do look at the micrometer reading on the tube before starting to be sure I wasn't dreaming and that it was set for 4.0 of the WW 231

Joe

[StarMetal]

Buckshot

I use to do like you said, weigh the charge, set the measure, then start loading, then recheck after ten or so to see if it changed. Well I quit that too, Belding & Mull measures, due to their design, don't change according to how much powder is in the main hopper. Their design, as I know you are aware of, has the main hopper, then a small reservoir that moves with the slide that dispenses the charge. They did this because it keep the powder density in the slide reservoir pretty constant.

One of the chemical plants that I worked in dealt in a powdered type product that got put in paper bags. Fifty pounds to the bag and they had an acceptable plus and minus factor. The bagging machine was automated. The giant hopper had a long tube on the bottom, think of a powder measure with a long long neck. This long neck had a valve at the top where it joined the hopper that shut it off from that hopper. It was in the shut off position when the bag was being filled. Let me tell you that machine run for hours throwing perfect weights. In a larger scale sense, that bagging machine hopper was like a Belding & Mull powder measure. I think whoever designed it had a knowledge of working with and weighing powdered products in industry.

Joe

[beagle]

First off, I may be old fashioned but I weigh EVERY charge of powder I put in a case.

The humidity (unless it's really high) shouldn't affect your charges very much at all.

When Petey was with us, he got all hyper about low humidity black powder one time. Average humidity here in KY where we live is about 68%.

He decided he'd shoot some low humidity loads. He got sealed ammo cans and a BUNCH of dessicant bags and had a meter that would measure humidity. Over a period of two weeks, he sucked the moisture out of a couple of pounds of black until it stabilized at about 20%.

He then ran tests in a .40/65 Sharpe's with the dry stuff (loaded and then stored in a desicant filled ammo can until just before firing).

Velocities ran about 200 FPS with the 20% stuff as opposed to the normal stuff stored in the reloading room.

I did notice that it pushed him about a bit more than normal and he got about an 18" flash out the muzzle.

Based on his tests, I'd say that smokeless is packed and tested under average conditions and I'd be surprised if there was a great amount of difference in weight gainned over a normal loading period unless the humidity was way up and then it would make for miserable loading anyway. Just my opinion.

I'm with Buckshot, I don't have anything that will throw charges that accurately anyway so I weight them all./beagle

[felix]

Joe, powder moisture makes a difference in volume measurements, not the energy content. Remembering the "click" graduation on a good measure is the volume measurement of that powder in energy terms, and is the amount to use. In other words, constant volume, not weight, decides the load to use. ... felix

[StarMetal]

Felix

Yup...but everyone still weighs to set that volume. If I don't change the lot of powder I'm using or change the setting on my measure, I don't. My Belding & Mull throws charges that good, the reason I've never bought another measure, like a Redding I've been eyeing up, but then said heck, this thing works great. Was just wanting a new toy to fool with.

Joe

[joeb33050]

Joe, powder moisture makes a difference in volume measurements, not the energy content. Remembering the "click" graduation on a good measure is the volume measurement of that powder in energy terms, and is the amount to use. In other words, constant volume, not weight, decides the load to use. ... felix
There's been a discussion of this on one or more of the BP forums, what I understand is that VOLUME rather than WEIGHT of powder must be kept constant for best accuracy. I think the underlying theory is that the DENSITY (weight/volume) of powder may vary as moisture content varies. A quart of powder may weigh 14 ounces to 16 ounces as the moisture content increases. But that quart has the same energy in it, no matter the weight, cause the added moisture that increases the weight doesn't add to the energy. This seems to be theoretical, does anybody have any objective evidence to confirm this theory?
joe b. in south Florida, with a part-full powder measure open to the high humidity for 4-5 hours each Wednesday

[felix]

Joe B, your analysis is correct. The name of powder control is density, in its formulation, lying in the case, etc., just about everywhere. ... felix

[fourarmed]

I bought a new can of H-110 once, and noted that it weighed a bit less than the same thrown volume from my old 8 pounder, which was getting low.
Out of curiosity, I poured a 4" line of each and lit them where they came together. They appeared to burn identically, but there was considerably more ash remaining where the old lot had burned. I thought about this a while, shrugged, and poured them together. I could see no difference in the performance of the loads.